A093011 Primes of the form 10*R_k + 3, where R_k is the repunit (A002275) of length k.

3, 13, 113, 11113, 111111113, 11111111113, 111111111111111111111113, 111111111111111111111111111111111111111111111111111111111111111111111111111111111113

Offset

1,1

Comments

Primes of the form 2 + (10^k - 1)/9, k > 0. - Vincenzo Librandi, Dec 13 2011

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..9

Makoto Kamada, Prime numbers of the form 11...113.

Index entries for primes involving repunits

Mathematica

Select[Table[(((10^n-1)/ 9)+2), {n, 1, 900}], PrimeQ] (* Vincenzo Librandi, Dec 13 2011 *)

Prog

(Magma) [a: n in [1..100] | IsPrime(a) where a is ((10^n-1) div 9)+2 ]; // Vincenzo Librandi, Dec 13 2011

Crossrefs

Cf. A056654 (corresponding k).

Sequence in context: A053583 A077713 A119723 * A262147 A364327 A057865

Adjacent sequences: A093008 A093009 A093010 * A093012 A093013 A093014

Keyword

nonn

Author

Rick L. Shepherd, Mar 14 2004

Status

approved